Processing of crude nickel-copper matte



United States Patent PROCESSING OF CRUDE NICKEL-COPPER MATTE Leo Schlecht and Helmut Schlecht, Ludwigshafen (Rhine), Germany, a'ssignors to Badische Anilin- & Soda-Fabrrk Aktiengesellschaft, Ludwigshafen (Rhine), Germany No Drawing. Application July 16, 1952, Serial No. 299,246

Claims priority, application Germany July 24, 1951 4 Claims. (Cl. 75-1) This invention relates to improvements in the working up of crude nickel-copper mattes.

The working up of copper crude materials containing iron, such as ores, which also contain nickel and/ or cobalt, is usually carried out by smelting to the so-called crude nickel-copper matte (green furnace matte). From this crude matte, which contains much iron besides copper, nickel and/ or cobalt and sulfur, the iron is wholly or for the most part converted to slag by blowing with air while adding 'silicic acid. In this way there is formed a nickelcopper or cobalt-copper refined matte free from or poor in iron, in which the metals copper, nickel and/or cobalt are considerably enriched so that the recovery of the individual metals is facilitated.

By working in this way, however, the whole of the amount of iron contained in the crude matte is obtained as iron silicate slag, the further Working up of which is usually not profitable. The iron contained in the crude material is thus lost. Moreover, since the slag obtained by blowing the crude matte to refined matte with the addition of silicic acid is always returned again to the crude matte smelting process, the amount of slag obtained by the crude matte smelting increases. Since, this slag always contains small amounts of copper, nickel and/or cobalt, the recovery of these metals from the crude material is appreciably worsened.

We have now found that the said drawbacks can be avoided by employing a crude matte the sulfur content of which is at the most sufficient for combining with the copper and iron contained therein but at least suflicient for combining with the copper contained therein, annealing this crude matte, then comminuting it and then subjecting it to a mechanical separation, such as by sieving, elutriation, flotation or magnetic separation. The surprising fact has been established that by adjusting the sulfur content of the crude matte to the said amount it is possible to segregate the nickel and/or cobalt contained in the crude matte, during the subsequent annealing treatment, in a predominantly metallic form as coarse particles which after comminution of the annealed matte can be separated by said mechanical means from the bulk of the iron and from the copper. In this way the whole of the metals contained in the crude matte, including the iron, can be obtained therefrom in individual fraction-s in which the individual metals are so enriched that they can be worked up further in the usual way.

The said adjustment of the sulfur content of the crude matte can be effected by decreasing the sulfur content of the crude matte by partial roast-ing and reducing the roasted product, whereby the oxide formed by the roasting is converted into metal. Slagging of the iron, such as took place hitherto by combination of the iron oxide formed with silicic acid, therefore does not take place. The sulfur content of the crude matte may also be reduced by the addition of metal in particular of iron and/or copper.

The annealing of the crude matte having a predetermined sulfur content can be carried out by slowly cooling 2,758,020 Patented Aug. 7, 1956 the fused crude matte. When doing this, it may be preferable to keep the matte for some time at a definite temperature, as for example between 400 and 900 C. Crude matte which is already cold may also be heated again and slowly cooled or kept at a definite temperature for some time. The annealing is continued until the metallic particles have as far as possible attained a size of more than 100 1.. When this is the case, also the other components of the annealed crude matte have usually attained a particle size which is sufficient for the subsequent mechanical separation.

The fraction containing nickel and/or cobalt, which contains more or less metallic iron depending on the sulfur content of the crude matte, is preferably separated by magnetic separation, while the fraction consisting mainly of copper sulfide and iron sulfide, which remains in the magnetic separation, can usually be split up into a product rich in copper and a product rich in iron by flotation.

Should there be formed by the magnetic separation middle fractions which contain nickel and/or cobalt and iron in metallic form besides iron sulfide and copper sulfide, it is in many cases more preferable to mix these middle fractions as metal-containing additions to the crude matte to be melted than toattempt by further comminution and repeated magnetic separation to separate in this case.

this nickel and/or cobalt content as higher-percentage metal.

The individual fractions thus obtained can be worked up in the usual way, for example in order to recover the individual metals separately. The fraction enriched in nickel and/ or cobalt can be directly employed with advantage as ferronickel or ferrocobalt for the production of alloy steels. Pure nickel or pure cobalt or a nickelcobalt alloy can be recovered without difliculty from this fraction containing nickel and/or cobalt by known methods. In this case it may be preferable-to decrease the iron content of this fraction by adjutsing the sulfur content of the crude matte to the above-mentioned upper limit.

In many cases however a higher iron content in this fraction should be arranged by adjusting a lower sulfur content of the crude matte because'with a higher iron content the growth of the grains containing nickel metal and/or cobalt metal is favoured during the thermal annealing. The duration of the annealing can be shortened The magnetically separated material thus obtained contains, besides metallic nickel, metallic iron. It can be worked up to pure nickel with special advantage according to the carbonyl process, for example by volatilizing the nickel from this fraction with carbon monoxide at pressures and temperatures at which the iron is not yet nickel-containing steels, or it can be added again as a metal addition to the crude matte melt in order to decrease the sulfur content thereof according to the above prescriptions and thereby to convert, for example, nickel sulfide present in the crude matte into nickel metal.

The metallic fraction enriched with nickel and/ or cobalt may also be worked up by treatment with acids or salt solutions or by anodic dissolution.

The sulfidic parts, which remain in the separation of the fraction containing the nickel and/ or cobalt and which contain practically the whole of the copper from the crude matte and a large part of the iron, may be separated for example by flotation and then worked up in the usual way for example into metallic copper and metallic iron, processes and apparatus hitherto usual being applicable also to these purposes.

The following example will further illustrate this invention but the invention is notlimited to this example.

Example To a nickel-copper crude matte being in the molten state and obtained from a sulfidic, iron-containing nickelcopper ore, there are added 18% of metallic iron; whereby a nickel-copper crude matte is formed containing 8.3% of nickel, 5.1% of copper, 60% of iron and the remainder sulfur. This molten crude matte is cooled in such manner that the fall in temperature amounts to about 5 C. per hour. After this thermal treatment, the crude matte, as may be detected from a microscopic section, consists of three different kinds of individual particles, namely metallic nickel-iron particles, copper sulfide particles and iron sulfide particles, the size of which amounts to more than 100/L. After comminution of this crude matte to a grain size of about 150 there may be separated by magnetic separation a fraction which contains 32.6% of nickel and 59% of iron besides small amounts of copper and sulfur. In this product the nickel content has therefore been enriched to four times as compared with the crude matte. By a treatment with carbon monoxide under pressure, 96.5% of the nickel contained therein is obtained as nickel carbonyl. The residue freed from nickel consists mainly of iron with small amounts of copper and sulfur and is melted in to further amounts of crude matte as a metallic addition instead of the corresponding amount of metallic iron.

What we claim is:

l. A process for Working up a green furnace matte containing in relative proportions, a major proportion of iron, and a minor proportion of copper and at least one of the metals nickel and cobalt, which comprises providing a sulfur content in said matte which is at least sutficient to combine with the copper contained therein but not greater than that sufficient to combine with the copper and iron contained therein, subsequently annealing said matte being substantially free of oxides of the metals and containing the metals in the form of sulfides and in the elemental state, by heating it at a temperature of about 400 C. to 900 C. for a period of time sufiicient to cause the formation in said matte of individual sulfidic particles including copper sulfide particles and individual metallic particles containing at least one of metallic nickel and metallic cobalt corresponding to the components of the initial matte, comminuting the annealed matte, and mechanically separating the said metallic particles from the said sulfidic particles.

2. A process for working up a green furnace matte containing in relative proportions, a major proportion of iron, and a minor proportion of copper and at least one of the metals nickel and cobalt, which comprises providing a sulfur content in said matte which is at least sufficient to combine with the copper contained therein but not greater than that sufiicient to combine with the copper and iron contained therein, subsequently annealing said matte being substantially free of oxides of the metals and containing the metals in the form of sulfides and in the elemental state, by heating it at a temperature of about 400 C. to 900 C. for a period of time sufficient to cause the formation in said matte of individual sulfidic particles including copper sulfide particles and individual metallic particles containing at least one of metallic nickel and metallic cobalt corresponding to the components of the initial matte, said metallic particles having attained substantially as completely as possible a grain size greater than about 100 microns, comminuting the annealed matte, and mechanically separating the said metallic particles from the said sulfidic particles.

3. A process for working up a green furnace matte containing in relative proportions, a major proportion of iron, and a minor proportion of copper and at least one of the metals nickel and cobalt, which comprises providing a sulfur content in said matte while molten which is at least sufiicient to combine with the copper contained therein but not greater than that sufiicient to combine with the copper and iron contained therein, subsequently slowly cooling said matte being substantially free of oxides of the metals and containing the metals in the form of sulfides and in the elemental state, from the molten state through the temperature range 900 C. to 400 C. to produce in the matte individual sulfidic particles including copper sulfide particles and individual metallic particles containing at least one of metallic nickel and metallic cobalt corresponding to the components of the initial matte, comminuting the matte, and mechanically separating the said metallic particles from the said sulfidic particles.

4. A process for working up a green furnace matte containing in relative proportions, a major proportion of iron, and a minor proportion of copper and at least one of the metals nickel and cobalt, which comprises providing a sulfur content in said matte While molten which is at least sutficient to combine with the copper contained therein. but not greater than that sufiicient to combine with the copper and iron contained therein, subsequently cooling said matte being substantially free of oxides of the metals and containing the metals in the form of sulfides and in the elemental state, from the molten state through the temperature range 900 C. to 400 C. at a rate of about 5 C. per hour to produce in the matte individual sulfidic particles including copper sulfide particles and individual metallic particles containing at least one of metallic nickel and metallic cobalt corresponding to the components of the initial matte, said metallic particles having attained substantially as completely as possible a grain size greater than about microns, comminuting the matte, and mechanically separating the said metallic particles from the said sulfidic particles.

References Cited in the file of this patent UNITED STATES PATENTS 1,518,626 Whitley Dec. 9, 1924 1,976,735 Kuzell Oct. 16, 1934 2,239,626 Schlecht et al. Apr. 22, 1941 2,245,503 Schlecht et al. June 10, 1941 2,295,219 Kalling et al. Sept. 8, 1942 2,419,973 Sproule et al. May 6, 1947 FOREIGN PATENTS 122,335 Great Britain Jan. 23, 1919 

3. A PROCESS FOR WORKING UP A GREEN FURNACE MATTE CONTAINING IN RELATIVE PROPORTIONS, A MAJOR PROPORTION OF IRON, AND A MINOR PROPORTION OF COPPER AND AT LEAST ONE OF THE METALS NICKEL AND COBALT, WHICH COMPRISES PROVIDING A SULFUR CONTENT IN SAID MATTE WHILE MOLTEN WHICH IS AT LEAST SUFFICIENT TO COMBINE WITH THE COPPER CONTAINED THEREIN BUT NOT GREATER THAT THAN SUFFICIENT TO COMBINE WITH THE COPPER AND IRON CONTAINED THEREIN, SUBSEQUENTLY SLOWLY COOLING SAID MATTE BEING SUBSTANTIALLY FREE OF OXIDES OF THE METALS AND CONTAINING THE METALS IN THE FORM OF SULFIDES AND IN THE ELEMENTAL STATE, FROM THE MOLTEN STATE THROUGH THE TEMPERATURE RANGE 900* C. TO 400* C. TO PRODUCE IN THE MATTE INDIVIDUAL SULFIDIC PARTICLES INCLUDING COPPER SULFIDE PARTICLES AND INDIVIDUAL METALLIC PARTICLES CONTAINING AT LEAST ONE OF METALLIC NICKEL AND METALLIC COBALT CORRESPONDING TO THE COMPONENTS OF THE INITIAL MATTE, COMMINUTING THE MATTE, AND MECHANICALLY SEPARATING THE SAID METALLIC PARTICLES FROM THE SAID SULFIDIC PARTICLES. 